At the 2019 ESMO Congress held in Barcelona, Spain, enlightening results were shared by Dr. Hope S. Rugo, MD, regarding the activity of atorolimumab (Tecentriq) and nab-paclitaxel (Abraxane) in a substudy of patients with triple-negative breast cancer (TNBC) who had immune cell PD-L1 expression by the SP142 immunohistochemistry (IHC) assay.

In comparison to the SP142 assay, Dr. Rugo, director of Breast Oncology Clinical Trials Investigation at the University of California, San Francisco Helen Diller Family Comprehensive Cancer Center, says: “the 22C3 and SP263 PD-L1 assays identified a greater patient population, and SP142 positivity was encompassed within the positive tests for both of these antibodies.”

Understanding these biomarkers can help clinicians “to demonstrate clinical benefit of immunotherapy in patients,” as reported in The OncLive. “However, questions remain about how to best identify patients who can benefit from this combination of atezolizumab and nab-paclitaxel,” Rugo said.

Study Results

“Clinical outcomes were evaluated in biomarker evaluable subpopulations with the following results:

  • Among patients who were positive for PD-L1 by both SP142 and 22C3, the absolute benefit with the addition of atezolizumab on median PFS was 4.4 months and the absolute benefit on OS was 9.3 months.
  • Among those whose tumors were positive for PD-L1 by 22C3 alone, the absolute benefit for PFS was 1.7 months and there was no difference in OS.
  • As expected, among patients whose tumors were negative by both SP142 and 22C3, there was no advantage on median PFS and median OS with the addition of the checkpoint inhibitor.
  • Among patients who were positive for PD-L1 by both SP142 and SP263, the absolute benefit with the addition of atezolizumab on median PFS was 4.2 months and the absolute benefit on median OS was 9.4 months.
  • Among those whose tumors were positive for PD-L1 by SP263 only, the absolute benefit for median PFS was 1.6 months and there was no difference in median OS.
  • Negativity for PD-L1 by both SP142 and SP263 predicted no benefit from the addition of atezolizumab.”

Presenter

Dr. Hope S. Rugo, MD, director of Breast Oncology Clinical Trials Investigation at the University of California, San Francisco Helen Diller Family Comprehensive Cancer Center

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Source: The OncLive

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